Revert "Set oom_score_adj of chrome processes directly"

This reverts commit 0f6c2c59656fb462932cf57262e8c1b2f9c3b46f.

Reason for revert: crash on OnFocusTabScoreAdjustmentTimeout

Bug: 869037

Original change's description:
> Set oom_score_adj of chrome processes directly
> 
> Setting oom_score_adj directly is faster and doesn't have to involve
> debugd when ARC++ is disabled.
> 
> Bug: 868249
> Change-Id: Ifeda6cd1d393c85f373928aafadd4ec3d3941a92
> Reviewed-on: https://chromium-review.googlesource.com/1152751
> Reviewed-by: Cheng-Yu Lee <cylee@chromium.org>
> Commit-Queue: Vovo Yang <vovoy@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#578987}

TBR=cylee@chromium.org,vovoy@chromium.org

Change-Id: Iafc37f22743479ba558fcc520bd24e7a30bcc693
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 868249
Reviewed-on: https://chromium-review.googlesource.com/1155327
Reviewed-by: Jun Mukai <mukai@chromium.org>
Commit-Queue: Vovo Yang <vovoy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#579090}
1 file changed